Field of the Invention
The present invention relates to a handheld apparatus for simultaneous tensioning the jackbolts of a multi-jackbolt tensioner and method of using same.
Background Information
Multi-Jackbolt Tensioner
A Multi-Jackbolt Tensioner (MJT) 10, such as sold under the Superbolt® brand, is generally used as a direct replacement for hex nuts, covered nuts, bolts, etc. of a size typically of 1″ or greater; a representative example of an MJT 10 is shown in FIG. 1. A conventional (nut based) MJT 10 spins onto existing bolt or stud (not shown) providing a distinct method to “bolt up the joint”. The typical MJT 10 consist of three components, i) a hardened washer 12 (or similar surface) to provide a hardened, flat surface for the jackbolts 16 to “push” against; ii) an often round nut body 14 that spins onto the existing bolt or stud and seats against the washer 12 hand tight in the original positioning; and iii) an annular array of jackbolts 16 that thread through the nut body 14 and are used to tighten the joint in pure tension. As noted, technically this is a nut version of an MJT 10 and there is a bolt version in which the nut body 14 is replaced with a threaded bolt body 14 threading into a threaded receiver. There can be other specialized versions of MJTs 10, such as thrust collar types, which are all included in the broad definition of an MJT 10, the operational distinctions of which are not critical for this discussion, as the present method and apparatus are applicable for all MJTs 10.
MJTs 10 have been described as eliminating the need for high powered and unsafe tooling, which increases worker safety and has been described as especially beneficial in applications with awkward locations. An MJT 10 takes the high preload requirements in large diameter bolting and breaks it down into manageable torques using the jackbolts 16 threaded through the body 14. In operation of a nut version of an MJT 10, the hardened washer 12 is installed first. Then the nut body 10 is threaded onto the existing stud or bolt, generally hand tight against the washer 12. The jackbolts 16 are then tightened and thrust against the hardened washer 12 to tension the joint. Accurate preload is achieved on the stud by torquing the individual jackbolts 16. Further discussions on the construction, operation and other aspects of MJTs 10 are found in U.S. Pat. Nos. 4,622,730, RE33,490, 4,927,305, 5,075,950, 5,083,889 and 6,112,396, which are incorporated herein by reference.
While MJTs 10 have eliminated the need for high powered tools they have introduced other issues to be addressed. For example, each jackbolt 16 of the MJT 10 must be separately tightened. In an application which implements multiple MJTs 10, the tightening of each jackbolt 16 can become time consuming, although not requiring high powered tooling. Consider a large assembly having ten bolts, each bolted using an MJT 10 with ten jackbolts 16, in this arrangement there are 100 individual jackbolts 16 to be tightened, each tightened to a designated tension.
Additionally, jackbolts 16 cannot be tightened in a manner that unbalances the nut body 14, thus they are often tightened in an alternating pattern, generally analogous to the well known “star pattern” used to tightened lug nuts of an automobile tire to prevent an unbalanced tire mounting. This specialized tightening method adds complexity to the tightening methodology for MJTs 10.
MJTs 10 provide a great advantage in many applications, however there remains a need to effectively and efficiently secure or tighten MJTs 10.
Multiple Fastener Drivers
It has been proposed to tighten multiple fasteners with a single tool. For example, U.S. Pat. No. 6,834,567, which is incorporated herein by reference, notes that machine tools with multiple spindles are used in assembly processes to tighten many fasteners at one time. These prior multiple spindle tools are quite often ineffective and such tools will often under-tighten one or more of the fasteners. This defect in multiple fastener tool design often leads to the inspector or the operator to use a separate tool to tighten the incorrect fasteners. In many instances, the manufacturer has resorted to using a single spindle nut runner in place of a multiple spindle tool. This solution results in a more time consuming operation.
U.S. Pat. No. 6,834,567 addresses this problem and discloses a single motor employed to drive a plurality of spindles with a gear arrangement placed between the motor and the spindles. The gear arrangement is comprised of a central gear, also known as a sun gear, and three planet gears fixed in a common carrier. In this design the central gear has a pitch circle smaller than the pitch circle of the planetary gears resulting in a minimal number of planetary gears that can be used, namely three planetary gears. Additionally each of the spindles has an input shaft and an output shaft and an adjustable in line reversible slip clutch is positioned between the input shaft and output shaft for each of the spindles. The design of U.S. Pat. No. 6,834,567 is not useful for MJT because the design is essentially limited to the three spindles as shown.
A review of proposed multi-fastener designs, and some related designs, may be beneficial for the present disclosure and understanding the advantages of the present invention. An alternative multi-fastener design is disclosed in U.S. Pat. No. 2,069,882 which discloses a wrench for tightening a plurality of securing members that includes a plurality of rotatable spindles operable to transmit tightening forces to the securing members, and a transmission operable by a single drive to rotate the several spindles independently to tighten the members to the same degree of tightness. The transmission includes pinions associated with the spindles, and an element, rotated by the drive, operable to successively cooperate with pairs of substantially opposite pinions to partially rotate the same.
U.S. Pat. No. 2,781,682 discloses a torque wrench with multiple spindles that provides a steady torque for setting screw-threaded fastenings while allowing the drive to slip when the fastening is tight.
U.S. Pat. No. 3,845,673 discloses a two-speed nut runner that has a low torque clutch designed for disengagement at a predetermined, relatively low torque. A second high torque clutch automatically takes over the transmission of torque at a lower speed and higher torque while holding the low torque clutch in a fully released position by means of a piston that is placed inside the output shaft of the nut runner.
U.S. Pat. No. 3,905,254 discloses a tool for loosening and removing the lug nuts of an automobile and truck wheels with selectively positioned non-rotating stabilized sockets.
U.S. Pat. No. 4,533,337 discloses a hydraulic torque impulse tool having a power inertia drive member, a hydraulic fluid chamber, and a cam driven piston in the fluid chamber for reciprocating movement.
U.S. Pat. No. 4,909,105 discloses an automated nut driving apparatus having a plurality of motors for rotating respective ones of a plurality of drive shafts to respective sockets holding nuts. The nut driver includes a plurality of universal joints connecting the sockets and drive shafts while allowing the sockets to be tilted with respect to the drive shafts. Universal joints are movable axially with respect to the drive shafts to allow the sockets to be retracted under reactive forces produced when the nuts engage the wheel attachment bolts.
U.S. Pat. No. 4,989,478 discloses an apparatus for tightening or loosening a plurality of bolts or other rotatable elements in which a drive socket and pair of reaction sockets are supported by an elongated beam member.
U.S. Pat. No. 5,092,410 discloses a hydraulic torque impulse generator using a dual piston arrangement to provide impacts to a rotatable anvil. Automatic shut-off and control apparatus is provided for limiting the pressure without reversing the direction of the driving clutch cage. A pressure venting arrangement permits one impact per revolution.
U.S. Pat. No. 5,125,298 discloses an automatic wheel assembly line in which an array of fastener members is prepared, corresponding in number and geometric pattern to the array of co-acting fastener members on the vehicle hub and to the array of bolt holes on the wheel assembly. The assembly includes a source of fasteners, a feeder mechanism having an outboard face, means defining a plurality of fastener receptacles, means operative to transport fasteners and means to move the loaded fasteners.
U.S. Pat. No. 5,572,905 discloses a torque driver including a laterally displaceable gear support member to carry an output spur gear. A biasing assembly biases the output spur gear into engagement with a pinion to which is applied an input torque greater than a desired output torque limit for a threaded fastener such as a nut or screw. A coiled output linkage connects the output spur gear with a fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. A gauged selector mechanism is provided to laterally displace multiple driver members for fasteners arranged in differing configurations. The torque limit is adjustable and may be set different for fasteners within the same fastener configuration.
U.S. Pat. No. 6,253,644 discloses a torque wrench including a main housing with two or more preset torque devices which establishes a torque range. A drive shaft protrudes from the main housing and drives a drive gear disposed in the main housing in which when rotated, drives the geared torque devices positioned on either side of the drive gear. A helical spring connects two torque pistons and adjustably applies a regulated torque to the driven torque piston in response to movement of the drive torque piston.
U.S. Pat. No. 7,628,097 discloses a bolt-tightening tool for tightening two bolts at the same time. The bolt-tightening tool includes a first rotating shaft coupled with a motor shaft and a second rotating shaft coupled with a motor case. A first bolt is tightened with the first rotating shaft, while a second bolt is tightened with the second rotating shaft, whereby the first and the second bolts are tightened with a same amount of torque.
U.S. Published Pat. App. No. 2006-0169107 discloses a bolt tightening device which includes bolt tightening mechanisms, a torque input unit, a toothed belt and torque transmission units. The torque transmission units are provided with toothed pulleys and are integrated with the bolt tightening mechanisms. A toothed pulley is fixed to the torque input unit, and connected to all the toothed pulleys of the plural torque input units by the single toothed belt. Torque input to the torque input unit is transmitted to the bolt tightening mechanisms by the toothed belt, and used to simultaneously tighten, for example, seven bolts.
Thus the concept of a multiple fastener drivers, or multi-nut drivers, which simultaneously drive two or more fasteners, or nuts, is well known. However none of these existing designs are well suited for MJT application. The design of these prior art devices does not allow them to be adapted for conventional MJTs 10.
There is a need to provide a multiple nut driver that is designed to accommodate all of jackbolts 16 of an MJT 10, for simultaneous driving of all of the jackbolts 16. There is a need to have the jackbolts 16 of an MJT 10 to be driven to a designated torque with a multiple nut driver. There is need to have such a tool be hand held.